I A Murdoch

Guy's and St Thomas' NHS Foundation Trust, Londinium, England, United Kingdom

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Publications (136)721.74 Total impact

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    ABSTRACT: Clonidine is a useful analgesic-sedative agent; however, few data exist regarding its use in infants after congenital heart disease surgery. We thus aimed to assess the absorption and safety of enterally administered clonidine in this setting.
    BJA British Journal of Anaesthesia 07/2014; · 4.24 Impact Factor
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    ABSTRACT: Prior to Norwood 1 surgery, neonates with hypoplastic left heart syndrome (HLHS) are at risk of decompensation from systemic underperfusion secondary to pulmonary overcirculation. We examined whether preoperative temporal profiles of physiological and laboratory variables differed between neonates who did and did not decompensate preoperatively.
    Archives of Disease in Childhood - Fetal and Neonatal Edition 07/2014; · 3.45 Impact Factor
  • R Saxena, A Durward, I Murdoch, S Tibby
    Critical Care 03/2013; 17(2). · 4.93 Impact Factor
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    ABSTRACT: BACKGROUND: /st>Pressure recording analytical method (PRAM) is a novel, arterial pulse contour-based method for measuring cardiac output (CO). Validation studies of PRAM in children are few, and have not assessed both absolute accuracy and ability to track changes in CO across a broad case mix. We aimed to compare CO as measured by PRAM with that using a transpulmonary dilution method in a cohort of critically ill children. METHODS: /st>Forty-eight, mechanically ventilated children with a median (inter-quartile) weight of 10.7 (5.5-15) kg with arterial and central venous catheters in situ were studied. CO was measured simultaneously using PRAM and the comparator method, transpulmonary ultrasound dilution (UD). Measurements were repeated before and after therapeutic interventions that were intended to augment CO (e.g. fluid bolus). RESULTS: /st>In total, 210 paired measurements were compared. The mean (sd) CO was 1.9 (1.2) litre min(-1) with UD when compared with 1.92 (0.5) litre min(-1) using PRAM. The mean bias was 0.02 litre min(-1) with wide limits of agreement: ±2.21 litre min(-1), giving a percentage error of 116%. The concordance between PRAM and UD for measuring changes in CO was also poor, with only 37% of measurements falling within the pre-defined polar plot limits of ±30°. CONCLUSIONS: /st>There is an unacceptably poor agreement between UD and PRAM. We do not recommend the use of PRAM for measuring CO in critically ill children with the current algorithm.
    BJA British Journal of Anaesthesia 11/2012; · 4.24 Impact Factor
  • Australian Critical Care. 05/2012; 25(2):140.
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    Critical Care 04/2012; 4:1-2. · 4.93 Impact Factor
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    Critical Care 01/2011; · 4.93 Impact Factor
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    Critical Care 01/2011; · 4.93 Impact Factor
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    ABSTRACT: Cerebral oedema is a potentially devastating complication of diabetic ketoacidosis (DKA). The relationship between osmolar changes, acid-base changes and development of cerebral oedema during therapy is unclear. Retrospective cohort study on 53 children with severe DKA (mean pH at presentation 6.92±0.08). Cerebral oedema was diagnosed using neurological status, response to osmotherapy, and neuroimaging, and classified as: early (occurring ≤1 h after presentation, n=15), late (1-48 h, n=17) or absent (controls, n=21). The temporal profiles for various osmolar and acid-base profiles were examined using a random coefficients fractional polynomial mixed model, adjusted for known risk factors. The three groups could not be differentiated by demographic, osmolar or acid-base variables at presentation. All osmolar and acid-base variables showed non-linear temporal trajectories. Children who developed late onset oedema showed dramatically different temporal profiles for effective osmolality and glucose-corrected serum sodium (both p<0.001). Glucose-corrected sodium provided better qualitative discrimination, in that it typically fell in children who developed late oedema and rose in controls. The maximum between-group difference for both variables approximated the median time of clinical cerebral oedema onset. Blood glucose and acid-base temporal profiles did not differ between the groups. Late onset oedema patients received more fluid in the first 4 h, but this did not influence the osmolar or glucose-corrected sodium trajectories in a predictable fashion. Glucose-corrected serum sodium may prove a useful early warning for the development of cerebral oedema in DKA.
    Archives of Disease in Childhood 10/2010; 96(1):50-7. · 3.05 Impact Factor
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    ABSTRACT: Mediastinal bleeding is common after pediatric cardiopulmonary bypass (CPB) surgery. Thromboelastography (TEG) may predict bleeding and provide insight into likely mechanisms. We aimed to (a) compare perioperative temporal profiles of TEG and laboratory hemostatic variables between patients with significant hemorrhage (BLEED) and those without (CONTROL), (b) investigate the relationship between TEG variables and routine hemostatic variables, and (c) develop a model for prediction of bleeding. TEG and laboratory hemostatic variables were measured prospectively at 8 predefined times for 50 children weighing <20 kg undergoing CPB. Patients who bled demonstrated different TEG profiles than those who did not. This was most apparent after protamine administration and was partly attributable to inadequate heparin reversal, but was also associated with a significantly lower nadir in mean (sd) fibrinogen for the BLEED group compared with CONTROL group: 0.44 (0.18) and 0.71 (0.40) g/L, respectively (P = 0.01). Significant nonlinear relationships were found between the majority of TEG and laboratory hemostatic variables. The strongest relationship was between the maximal amplitude and the platelet-fibrinogen product (logarithmic r(2) = 0.71). Clot strength decreased rapidly when (a) fibrinogen concentration was <1 g/L, (b) platelets were <120 x 10(9)/L, and (c) platelet-fibrinogen product was <100. A 2-variable model including the activated partial thromboplastin time at induction of anesthesia and TEG mean amplitude postprotamine discriminated well for subsequent bleeding (C statistic 0.859). Hypofibrinogenemia and inadequate heparin reversal are 2 important factors contributing to clot strength and perioperative hemorrhage after pediatric CPB. TEG may be a useful tool for predicting and guiding early treatment of mediastinal bleeding in this group.
    Anesthesia and analgesia 02/2010; 110(4):995-1002. · 3.08 Impact Factor
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    Critical Care 01/2009; 13. · 4.93 Impact Factor
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    ABSTRACT: Metabolic acidosis is common in septic shock, yet few data exist on its etiological temporal profile during resuscitation; this is partly due to limitations in bedside monitoring tools (base excess, anion gap). Accurate identification of the type of acidosis is vital, as many therapies used in resuscitation can themselves produce metabolic acidosis. Retrospective, cohort study. Multidisciplinary pediatric intensive care unit with 20 beds. A total of 81 children with meningococcal septic shock. None. Acid-base data were collected retrospectively on 81 children with meningococcal septic shock (mortality, 7.4%) for the 48 hrs after presentation to the hospital. Base excess was partitioned using abridged Stewart equations, thereby quantifying the three predominant influences on acid-base balance: sodium chloride, albumin, and unmeasured anions (including lactate). Metabolic acidosis was common at presentation (mean base excess, -9.7 mmol/L) and persisted for 48 hrs. However, the pathophysiology changed dramatically from one of unmeasured anions at admission (mean unmeasured anion base excess, -9.2 mmol/L) to predominant hyperchloremia by 8-12 hrs (mean sodium-chloride base excess, -10.0 mmol/L). Development of hyperchloremic acidosis was associated with the amount of chloride received during intravenous fluid resuscitation (r = .44), with the base excess changing, on average, by -0.4 mmol/L for each millimole per kilogram of chloride administered. Hyperchloremic acidosis resolved faster in patients who 1) manifested larger (more negative) sodium chloride-partitioned base excess, 2) maintained a greater urine output, and 3) received furosemide; and slower in those with high blood concentrations of unmeasured anions (all, p < .05). Hyperchloremic acidosis is common and substantial after resuscitation for meningococcal septic shock. Recognition of this entity may prevent unnecessary and potentially harmful prolonged resuscitation.
    Critical Care Medicine 10/2007; 35(10):2390-4. · 6.12 Impact Factor
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    Critical Care 01/2007; 11. · 4.93 Impact Factor
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    ABSTRACT: To demonstrate the diagnostic yield, therapeutic role and safety of flexible bronchoscopy via an intensivist-led service in critically ill children. Retrospective chart review. Regional paediatric intensive care unit. One hundred forty-eight flexible bronchoscopies were performed by two intensivists on 134 patients (median age 16.5 months) over a 2.5-year period. Eighty-eight percent of patients required mechanical ventilation, and 22% were receiving inotropes. Case mix included general (n = 77), cardiac surgery (n = 18), cardiology (n = 13), ear-nose-and-throat surgery (n = 17), oncology (n = 8) and renal (n = 1). The indication for bronchoscopy was defined a priori according to one of four categories: suspected upper airway disease (n = 32); lower airway disease (n = 70); investigation of pulmonary disease (n = 25); and extubation failure (n = 21). Bronchoscopy was generally performed soon after PICU admission, at a median time of 1.5 days for the former three categories, and 4 days for extubation failure group. A positive yield from bronchoscopy (diagnosis that explained the clinical condition or influenced patient management) was present in 113 of 148 (76%) procedures, varying within groups from 44% (pulmonary disease) to 90% (extubation failure). Ten percent of patients developed a fall in oxygen saturations > 20% during the procedure and 17% required a bolus of at least 10 ml/kg of 0.9% saline for hypotension. Critically ill patients with respiratory problems may benefit from a PICU-led bronchoscopy service as the yield for positive bronchoscopic finding is high, particularly for upper airway problems or extubation failure.
    Intensive Care Medicine 01/2007; 32(12):2026-33. · 5.26 Impact Factor
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    O'Dell E, Tibby SM, Durward A, Murdoch IA
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    ABSTRACT: An abstract is unavailable. This article is available as HTML full text and PDF.
    Pediatric Critical Care Medicine 06/2006; 7(4):409. · 2.35 Impact Factor
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    ABSTRACT: During the acute treatment of diabetic ketoacidosis we (a) determined the temporal incidence of hyperchloraemia, and (b) quantified the influence of hyperchloraemia on interpretation of common blood gas derived acid base parameters, namely base deficit and bicarbonate. Retrospective chart review in two regional paediatric intensive care units. Stewart's physicochemical theory was used to develop regression equations quantifying the acidifying effect of hyperchloraemia on both base deficit and bicarbonate. These were then applied retrospectively to blood chemistry results from 18 children (median age 12.7 years, weight 43 kg) with diabetic ketoacidosis. Plasma ketonaemia was estimated using the albumin-corrected anion gap. The incidence of hyperchloraemia, as documented by a ratio of plasma chloride to sodium of greater than 0.79, increased from 6% at admission to 94% after 20 h of treatment. Correction for chloride produced a dramatic improvement in the relationship between changes in the anion gap vs. both base deficit (from R(2)=0.55 to R(2)=0.95) and bicarbonate (from R(2)=0.51 to R(2)=0.96) during treatment. After 20 h of treatment the mean base deficit had decreased from 24.7 mmol/l to 10.0 mmol/l however, the proportion that was due to hyperchloraemia increased from 2% to 98%. It is now possible using a simple correction factor to quantify the confounding effect of hyperchloraemia on both base deficit and bicarbonate in diabetic ketoacidosis. This bedside tool may be a useful adjunct to guide therapeutic interventions.
    Intensive Care Medicine 03/2006; 32(2):295-301. · 5.26 Impact Factor
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    Critical Care 01/2006; 10. · 4.93 Impact Factor
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    Critical Care 01/2006; 10. · 4.93 Impact Factor
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    J Davies, S M Tibby, I A Murdoch
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    ABSTRACT: Parental accompaniment during inter-hospital transportation (retrieval) of critically ill children is not commonplace in the United Kingdom. A three month pilot of parental accompaniment was undertaken in 2002 (143 retrievals), after which time the policy was adopted as standard practice. A follow up audit was performed in 2004 (136 retrievals). Findings were remarkably consistent between the two periods. Staff perceived little or no added stress during the majority of transfers (96% in 2002, 98% in 2004), and felt able to perform medical interventions without hindrance (98% in 2002, 100% in 2004). There was good agreement between medical and nursing staff regarding perception of stress and ability to perform interventions (phi statistic 0.57 to 1.00). Adverse events occurred during 11 (3.9%) retrievals; six of these involved a parent exclusively. Stress tended to be associated with adverse events or parental behaviour rather than disease acuity. Staff vetoed the offer of accompaniment on 11 occasions, for a variety of reasons. The majority of parents found the experience safe, beneficial, and perceived a reduction in stress as a result. These data may inform other retrieval services who are considering adopting a similar policy.
    Archives of Disease in Childhood 01/2006; 90(12):1270-3. · 3.05 Impact Factor
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    A Durward, D Taylor, S Tibby, I Murdoch
    Critical Care 01/2006; 10. · 4.93 Impact Factor

Publication Stats

2k Citations
721.74 Total Impact Points

Institutions

  • 2006–2013
    • Guy's and St Thomas' NHS Foundation Trust
      • Paediatric Intensive Care Unit (PICU)
      Londinium, England, United Kingdom
  • 1991–2011
    • London School of Hygiene and Tropical Medicine
      Londinium, England, United Kingdom
  • 2002–2005
    • The Bracton Centre, Oxleas NHS Trust
      Дартфорде, England, United Kingdom
  • 2004
    • Alder Hey Children's Healthcare Hospital
      Liverpool, England, United Kingdom